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A USER’S MANUAL FOR DELSOLS: A COMPUTER CODE FOR
CALCULATING THE OPTICAL PERFORMANCE AND OPTIMAL SYSTEM
DESIGN FOR SOLAR THERMAL CENTRAL RECEIVER PLANTS
I. Introduction
In central receiver systems, a large number of individually tracking mirrors,
called heliostats, are used to concentrate sunlight on a receiver at the top of a
tower. These systems have the potential to deliver thermal energy over a wide
range of power levels and temperatures. Applications include central station elec-
tric power generation, industrial process heat and production of fuels and chem-
icals. Analytical techniques for central receiver system design are required be-
cause it is impractical to investigate experimentally the wide ranges of design and
application alternatives for central receivers. Furthermore, the analysis must be
computer based because of 1) the large number (i. e., thousands) of heliostats in
many single system designs; 2) the strong time dependence of system performance
due to the motion of the sun; and 3) the large number of options which have to
be considered in optimal design. The DELSOL computer program was written to
fill the need for an accurate, yet fast, easy to use and documented code for per-
formance and design applications. Version I, which analyzed large power electric
applications, was released in August 1978. Version I1 improved and extended the
capabilities of Version I. Version I1 can handle both large and small power sys-
tems for electricity and process heat applications. The present Version I11 has
been updated to incorporate more up-to-date cost defaults, new component cost
and receiver loss relationships, more detailed parasitic loss calculations, and cor-
rections to known errors in Version 11. The code consists of a detailed model of
the optical performance, a simpler model of the non-optical performance, an al-
gorithm for field layout, and a searching algorithm to find the best system design.
The latter two features are coupled to a cost model of central receiver compo-
nents and an economic model for calculating energy costs.
Figure 1-1 indicates schematically how the components of DELSOL are used
in the two general classes of application. In (A), a complete system design (which
may have been previously optimized by DELSOL) is specified by the user, and
the code calculates its performance. Typical applications include design point
evaluation and analysis of experiments at test facilities. In (B), the heliostat de-
sign, the range of system variables to be optimized, and the design constraints are
specified by the user and the code calculates optimal designs for a range of power
levels. Typical applications include system optimization and component design
tradeoff studies.
As an optical performance tool, DELSOL simulates the effects of cosine, shad-
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